Coordinated hydraulic motor control system and pressure coordinating valve therefor



Nov. 5, 1968 H. G. INHOFER COORD I NATED HYDRAUL I C MOTOR CONTROLSYSTEM A PRESSURE COORDINATING VALVE THEREFOR 19, 1964 Original FiledNo' 2 Sheets-Sheet 1 I l m m ll; m .mn

. 2 2 m M I I M a MPH o I W 1 18 m G D M m L 4 L m [1! x .m 1 J r K H m7 n g u a FIEZE Nov. 5, 1968 H. G. INHOFER 3,408,901

COORDINATE.) HYDRAULIC MOTOR CONTROL SYSTEM AND PRESSURE CUORDINATINGVALVE THEREFOR 1 Filed Nov. 19, 1964 2 Sheets-Sheet 2 Urigina INVENTOR.//AROD 6. [VI/0P5! i ited States 3 408,901 CGORDINATED HliDRAULIC MOTORCON:

TROL SYSTEM AND PRESSURE COORDI- NATING VALVE THEREFOR Harold G.Inliofer, Eden Prairie, Minn., assignor to Hawk 5 Bilt Mfg. Corp., acorporation of Iowa Continuation of application Ser. No. 527,991, Feb.16, 1966, which is a continuation of application Ser. No. 412,418, Nov.19, 1964. This application Dec. 18, 1967, Ser. No. 697,547

13 Claims. (Cl. 91-412 10 ABSTRACT OF THE DISCLOSURE This application isa continuation of my copending patent application Ser. No. 527,991,filed Feb. 16, 1966, now abandoned, which in turn was a continuation ofmy patent application Ser. No. 412,418, filed Nov. 19, 1964, nowabandoned.

Background of the invention Many hydraulic systems require exertion offorces in two directions or two motions at the same time. This is truein a system for boring holes as both a rotary motion and an axial motionmust be provided. As long as these motions are unimpeded the hydraulicsystem works per fectly but when one of the motions becomes impeded thenthe system must be compensated in order to bring the system back intoproper working relation. In most cases this compensation is donemanually and thus requires a somewhat skilled operator. With the deviceof this invention it is possible to precorrelate the motion of tworelated hydraulic actuators such that when the action of one becomesimpeded a compensating factor will be automatically introduced such thatthe unit will overcome the impedance and return to the normal desiredoperating situation.

50 Summary of the invention In order to best illustrate the operation ofthis valve this invention is illustrated as controlling a hydraulicallyoperated post hole digger which is provided with a rotary auger and alift cylinder. It should initially be understood that the subject matterof this invention would beadaptable to many other devices which use atleast a pair of hydraulically actuated units whose operation isintegrated and related. Thus, the system of this invention may be usedin a trencher machine wherein the trencher is hydraulically driven andthe traction drive for the trencher is also hydraulically driven. Thesystem may also be used in a bottom silo unloader in which one hydraulicmotor drives a sweep arm that rotates about the bottom of the silo, andanother motor drives a cutter-auger 65 in the sweep arm to cut silageand feed it to the center of the silo where it drops through a hole inthe floor 'for removal from the silo. The correlation in such cases willbecome obvious as we describe the invention in this particularapplication.

It is therefore an object of applicants invention to atent provide anautomatic coordinating and control mechanism for a hydraulic systemwhich will normally provide hydraulic pressure to at least a pair ofhydraulic actuators to coordinate all the actuators in the connectedsystem in a predetermined pattern.

It is a further object of applicants invention to provide a hydraulicsystem wherein at least a pair of hydraulic actuators may be controlledin interrelated fashion such that a change in conditions for one of theactuators will be automatically compensated for in the other actuatoruntil the normal predetermined operating condition is achieved.

It is a further object of applicants invention to provide a system forcontrolling the operation of a pair of hydraulic motors which drive atool and a tool carrier in such a way that the tool carrier advances thetool into the work only when the tool drive motor produces apredetermined minimum back pressure due to load on the tool.

Yet a further object of applicants invention is to provide a hydrauliccontrol system in which each of a pair of hydraulic motors is controlledby its individual valve, and back pressure produced by the first motoracts through a pressure coordinating valve to control operation of thesecond motor independently of the valve for the second motor.

Still another object of the invention is to provide a hydraulic controlsystem in which a coordinating valve opens gradually in response toincreasing back pressure produced by load on a first motor, so as togradually start a second motor, and gradually closes to 'slow andfinally stop the second motor as back pressure from the first motorfirst approaches. and then reaches the top of a predetermined operatingpressure range; but in which a sudden surge of back pressure from thefirst motor can stop the second motor very rapidly.

It is a further object of applicants invention to provide a pressureresponsive bypass valve for automatically coordinationg a pair ofhydraulic actuators such that a predetermined relation of operation maybe attained and maintained between the hydraulic actuators.

Still a further object is to provide a pressure responsive coordinatingvalve in which a movable valve piston is urged in one direction by avolute compression spring which provides a positive stop when it isfully compressed so that no other stop for the piston is required.

Description of the drawings FIG. 1 is a fragmentary side elevationalview with parts broken away illustrating the connection of a hydraulicactuated post hole digger having a hydraulically actuated li-ft cylindermounted on the rear of a prime mover;

FIG. 2 is a schematic illustration of the conduit connections for thesystem embodying the concepts of this invention;

FIG. 3 is a longitudinal cross section of the compensating and controlmember for the system;

FIG. 4 is a transverse section taken substantially along line 4-4 ofFIG. 3.

Detailed description of the invention In accordance with theaccompanying drawings and illustrating the particular application ofthis hydraulic control system a post hole auger generally designated 10is mounted for vertical oscillation on a prime mover P through a supportbar 11 having its ends llb-lla pivoted respectively on the prime mover Pand a portion of the post hole auger 10. Rotary power is delivered tothe auger 10 through a hydraulic motor 12 mounted axially to the auger10. Lifting and lowering power is provided through the support bar 11 toauger throughv ahydraulic cylinder 13 havingone end 13a attached to thesupport arm 11 with the other end 13b attached to the prime mover P. Asource of hydraulic pressure S is provided on the prime mover P and thecontrols for the hydraulic fluid provided from the source S generallyincludes a coordinating valve 15, a lift cylinder control valve 16 andan auger control valve 17. Lift valve 16 and auger valve 17 are what isknown in the trade as three, position valves; the respective positionsbeing up, hold and down for the lift valve 16 and forward, hold andreverse for theauger valve 17. In the hold position the valves provide abypass situation permitting the flow .to pass therearound to establish acontinuous flow circuit from H to L, rather than a closed position.

Coordinating valve is illustrated in FIG. 3 and consists generally of atwo-part housing comprising an adjustment housing 20 and a valvinghousing portion 21 securely sealed together with a mounting plate 20apro- .vided on one end of the adjustment housing 20.

Valve housing portion 21 of the valve 15 includes a housing portionhaving a central passage 21a longitudinally therethrough with an inletopening 21b on one end thereof for attaching a hydraulic pressure linethereto.

An outlet connection 22 is provided in spaced relation from inlet end21b and is arranged on the outer periphery of housing 21 with a meteringpassage 23 permitting communication between the outlet 22 and thelongitudinal passage 21a through housing 21. An adjustable metering setscrew 24 as illustrated in FIG. 4, is provided to control communicationthrough passage 23.

ing the groove are beveled. An internal passage conduit 28 is formedcentrally of the valve piston from the inlet end 25b of valve 25 andextends upward therethrough to communicate with a radially formedpassage conduit 29 which communicates with the pressure passage groove27. In the normal inoperative position as shown in FIG. 3 the uppershoulder 27!: of groove 27 prevents communication between the groove anddischarge metering passage 23.

Internally of the adjustment housing 20 an adjustment mechanismgenerally designated 30 is provided. This mechanism 30 generallyincludes a handle member 31 extending through top cover 20a and havingthe lower end 31a thereof in abutting relation with and in controllingcommunication with a spring retaining and longitudinal guide member 32.Guide member 32 is arranged for longitudinal sliding movement withinadjustment housing 20 and has a boss member 32a arranged centrallythereon to receive a spring member 23 thereabout.

Within the opposite end of adjustment housing 20 a valve abutting member34 is provided and is slidable within adjustment housing 20. A boss 35on member 34 provides an abutting shoulder 35a for a spring member 33which is inserted over a smaller centering boss 36.

Spring member 33 is a volute compression spring made up of substantiallywide convolutes as would be provided from rolling a wide band into aspring. The end portion 33b of the spring is received about thecentering boss 36. This spring is a standard commercially available 1spring and by using this type of spring no other physical stops toprevent collapse of the adjustment device are necessary. This is due tothe fact that complete compression of spring 33 will form a tubular bodywith the side walls of the spring forming a tubular structure precluding further compression of the spring 33.

The function of the coordinating member 15 will now be described.Tension on the spring 33 is predetermined to make it possible to adjustthe spring 33 through handle 31 such that the spring 33 will notcompress until a predetermined force or pressure is receivedlongitudinally thereagainst. This pressure is in the form of hydraulicpressure acting on the inlet end 25b of valve piston 25 and receivedthrough inlet 21b. At low pressure no fluid will pass from groove 27into discharge passage 23 due to the closed position of the valve piston25. Upon reaching the predetermined fluid pressure, spring 33 iscompressed and valve piston 25 will be driven upwardly allowing fluid tobypass through passages 28-29, groove 27 and passage 23. Again at apredetermined pressure governed by the longitudinal length of the groove27 in combination with the spring constant, the lower shoulder 27a ofgroove 27 will slide upwardly to shut off communication to passage 23.Metering needle 24 further serves to control the discharge fluid.

FIG. 2 illustrates the coordinating features of this system. Lift valve16 and auger valve 17 are connected in series with a source S with thehigh pressure line H feeding directly into the lift valve 16 and the lowpres sure line L receiving fluid from auger valve 17. It should beobvious that this connection from source S could be two parallelconnections as no interconnections are made in these lines. First andsecond pressure lines LL and HL are directed from the lift valve 16 tothe lift cylinder 13 to respectively lower and raise the arms 11.Likewise a high pressure line and a low pressure line designated HA andLA are directed from the auger valve 17 to the auger motor 12. A highpressure bypass line designated HC interconnects high pressure line HAwith the inlet 21b of the compensator 15. Likewise a high pressure lineHD connects outlet 22 of the valve 15 with line LL to feed the liftcylinder 13 and lower the arms. A low pressure line LC connects thesecond pressure line HL with the low pressure line LA.

As stated, the function of the system shown in this application is tocontrol an automatic post hole digger and an operative description willnow be given.

Coordinating valve 15 is preadjusted to operate at an optimum pressureand the auger tip is lowered to the ground by moving lift valve 16 toadmit pressure fluid to line LL. Lift valve 16 is now shifted to thehold position and auger valve 17 is placed in the forward position toadmit pressure fluid to the line HA. As soon as an initial pressure isbuilt up in the system valve piston 25 of valve 15 is forced upwardlyand fluid begins to bypass through passages 2829, groove 27 anddischarge 23 and 22. This bypass fluid is delivered into the line LLfrom line HD and thus the lift cylinder 13 will force the auger 10downwardly at a constant rate even though lift valve 16 is in holdposition at this time. As lift valve 16 is in hold position and fluidmay not pass therethrough, the exhaust from lift cylinder 13 through HLis discharged through bypass line LC to join the discharge from augerline LA. Should the auger 10 run into diificult boring material, thepressure required to turn the auger 10 will increase in proportion tothe difficulty of boring. If this pressure build up is sufficient, theadded pressure will cause the valve piston 25 to move into its uppermostposition and seal discharge 23. In this situation no fluid passes toline HD and thus lift cylinder 13 is inoperative and the total pressureserves to rotate the auger 10 until it frees itself and causes thepressure to drop to likewise allow valve piston 25 to drop, being forceddownward by spring 33 to again permit bypass fluid to flow.

,It is apparent from the structure of the coordinating valve 15 and thebehavior of hydraulic systems that as pressure on the inlet end 25b ofthe piston 25 gradually increases above the minimum operating pressureestablished .by spring 33, the piston 25 will open only a small amountand thus apply relatively slight operating pressure to the lift'cylinder13 so as to move the auger 10 relatively slowly until the optimumpressure range is reached, at which point the piston 25 will advance theauger at maximum speed. At the upper end of the optimum pressure range,as the shoulder 27a defining the lower end of the groove 27 moves acrossthe discharge passage 23, the advance of the auger may be graduallyslowed, or it may be terminated quite rapidly, depending upon thesuddenness with which back pressure on the motor 12 increases. Thisprovides considerable flexibility in operation of the system.

It is apparent that the extent of the optimum pressure range dependsupon the length of the groove 27 in the piston 25. The bottom of theoptimum pressure range is reached when the shoulder 27b passes the topof the discharge passage 23, and the top of the optimum pressure rangeis reached when the shoulder 27a passes the bottom of the passage 23. Asseen in FIG. 3, the length of the groove 27 is substantially greaterthan the width of the passage 23, so that the structure does provide anoptimum maximum pressure range, rather than merely a single maximumpressure point as would be the case if the length of the groove 27 wereno greater than the diameter of passage 23.

Line LC is provided between the line HL of lift cylinder 13 and lowpressure line LA of motor 12 because when the lift valve 16 is in holdposition it will not pass fluid therethrough.

It is possible with this combination for the operator to override thecompensating arrangement through operation of the valves 16-17. To lowerarm 11 control valve 16 is shifted to the down position. To lift,however, the operator must either stop the auger or must reverse therotation of the auger 10. Accordingly, a check valve could be insertedin line LC if the operator would ever want to run the auger 10 in thenormal digging direction and still lift the auger 10.

Metering screw 24 is provided to allow variations between the capacityof the hydraulic motor 12 as compared to the capacity of the hydrauliccylinder 13. This, of course, will vary with the application and thetypes and uses of the hydraulic motors which are being coordinated. Themetering screw also permits adjustment of the level at which thecompensating valve opens and closes without adjusting the spring bychanging the passage 23, or for pressures above the level at which thespring would be fully compressed if the passage 23 were fully open.

The advantage of this type of system is, of course, to eliminate theskill of the operator ordinarily required through the usual systems andfurther that it is possible to obtain and operate the drive engine at amaximum torque by adjusting the coordinating valve such that operationis always at an optimum pressure.

Applications of this type of system and the coordinating valve memberare of course numerous. This system may be installed whenever it isdesired to integrate and coordinate the movements of at least a pair ofhydraulic actuators. The system may be substantially the same as thatdescribed for any application.

It will, of course, be understood that various changes may be made inthe form, details, arrangements and proportion of parts withoutdeparting from the scope of the invention, which-generally statedconsists in the matter set forth in the appended claims.

I claim:

1. A hydraulic pressure control system for interrelating the actions ofat least a pair of hydraulic actuators, said system comprising, incombination:

a source of hydraulic pressure;

individual valve means for respectively controlling pressure fluid flowto each of the actuators;

each of said valve means receiving fluid from the pressure source andhaving at least a first pressure connection to its respectivelycontrolled actuator; and

a pressure coordinating member interconnected with the first pressureconnection for a first of said actuators for delivery of fluid to thefirst pressure connection for a second of said actuators, saidcoordinating member being normally closed but opening in response toback pressure created by the first of said actuators to pass pressurefluid over a predetermined pressure range and closing at the upper limitof said range to permit the entire fluid pressure to be exerted only onsaid first actuator.

2. The system of claim 1 in which the coordinating member includes acontrol portion and a resilient member arranged in cooperatingcontrolling relation to said control portion whereby the control portionis normally urged into closed position.

3. The system of claim 2 which includes means for adjusting the tensionon said resilient member to thereby adjust the opening pressure for saidcontrol portion.

4. The system of claim 2 in which the resilient memher is a volutecompression spring which, when fully compressed, provides a solidtubular member affording a positive stop for the control portion.

5. The system of claim 1 in which the coordinating member includes ahousing, a control piston mounted for sliding movement in said housingin response to said back pressure and having a circumferential fluidcarrying groove, and a passage through the side of the housing in anarea where it is traversed by said groove during part of the movement ofsaid piston so as to pass fluid from said groove to the first pressureconnection for the second actuator; the relationship between said grooveand said passage being such that only a small volume of fluid passesthrough the passage near the lower and upper limits of the predeterminedpressure range, whereby the second actuator may operate slowly near bothends of said range and at maximum speed through the middle portion ofthe range.

6. A hydraulic pressure control system for coordinately operating a tooland feed means for said tool, said system comprising, in combination:

a first hydraulic actuator for driving said tool;

a second hydraulic actuator for advancing said feed means;

a source of hydraulic fluid under pressure;

a valve for controlling admission of hydraulic pres sure fluid from saidsource to said first actuator;

and a normally closed pressure coordinating valve which is opened inresponse to a predetermined back pressure created by operation of saidfirst actuator to admit hydraulic pressure fluid to said secondactuator, whereby said feed means is advanced only when said tool isoperating under conditions which create at least said predetermined backpressure, said coordinating valve remaining open through a predeterminedrange of back pressure, and closing when the back pressure reaches apredetermined value to stop the advance of the feed means when load onthe tool reaches a predetermined maximum level.

7. The system of claim 6 in which the coordinating valve includes ahousing, a control piston mounted for sliding movement in said housingin response to said back pressure and having a circumferential fluidcarrying groove, and a passage through the side of the housing in anarea where it is traversed by said groove during part of the movement ofsaid piston so as to pass fluid from said groove to the second actuator;the relationship between said groove and said passage being such thatonly a small volume of fluid passes through the passage near the lowerand upper limits of the predetermined pressure range, whereby the secondactuator may operate slowly near both ends of said range and at maximumspeed through the middle portion of the range.

8. A hydraulic pressure control system for interrelating the actions ofa pair of hydraulic actuators comprising, in combination:

a source of hydraulic pressure;

individual valve means respectively controlling pressure fluid flow toeach of the actuators;

each of said valve means having a hold position in which no fluidpressure is delivered to the actuator controlled by it, and at least oneactuating position in which fluid pressure is delivered through thevalve means to a first pressure connection of the actuator controlled byit; and

a pressure coordinating member interconnected with the first pressureconnection of a first of said actuators,

said member being normally closed but opening in response to backpressure created by said first actuator, and said coordinating memberwhen open being connected to deliver hydraulic pressure to the firstpressure connection of said second actuator independently of the valvemeans for said second actuator.

9. The system of claim 8 in which the pressure coordinating member isconstructed and arranged to terminate delivery of hydraulic pressure tothe second actuator when back pressure created by the first actuatorexceeds a predetermined value.

10. A pressure coordinating valve for controlling the flow of fluid overa predetermined pressure range comprising, in combination:

a valve housing having a fluid inlet opening and a fluid outlet opening;

an adjustment housing at one end of the valve housing;

a valve member slidable in said valve housing toward and from theadjustment housing and having a circumferential fluid flow groove, saidmember being longitudinally slidable between a first position in whichit seals the valve housing against communication between the inlet andoutlet openings, a second position in which fluid may pass between saidinlet and outlet openings through said groove, and a third position inwhich it again seals communication between said inlet and outletopenings, said valve member having an inlet end exposed to fluidpressure from the inlet opening and a second end facing the adjustmenthousing; means sealing the adjustment housing from the inlet and outletopenings; compression spring means in the adjustment housing that bearsagainst the second end of the valve member and provides the sole forceopposing inlet fluid pressure; and means for adjusting said spring meansto vary the force that opposes inletfluid pressure. 11. The valve ofclaim 10 in which the inlet is at the end of the valve housing oppositetheadjustment housing, and the valve member includes fluid flow passagesfrom the first end of the valve into the fluid flow grooves. 12. Thevalve of claim 10 in which the outlet: opening is in the wall of thevalve housing in an area which is traversed by the fluid flow groove ofthe valve member, said groove being substantially larger than the widthof said opening so that maximum fluid flow through said opening may takeplace throughout a predetermined. range. 13. The valve of claim 10 inwhich the spring means is a volute compression spring which, when fullycompressed, provides a solid tubular member affording a positive stopfor the valve member.-

References Cited Weaver et a1. 214-17.82

EDGAR w. GEOGHEGAN, Primal Examiner.

